Operating Segments and Related Information (Details 2) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	$ 464,712	$ 405,228	$ 1,305,650	$ 1,187,429
Intersegment revenue	0	0	0	0
Earnings from operations	87,086	80,849	212,802	203,438
Surveillance
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	146,805	136,402	394,742	373,993
Intersegment revenue	(10,115)	(5,001)	(18,203)	(13,980)
Earnings from operations	44,941	41,428	104,313	103,888
Instruments
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	91,429	82,673	255,253	240,160
Intersegment revenue	(929)	(709)	(2,916)	(3,498)
Earnings from operations	29,603	27,578	74,376	67,254
Security
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	65,660	56,431	160,447	166,872
Intersegment revenue	(2,931)	(4,267)	(9,697)	(10,575)
Earnings from operations	6,486	4,784	8,090	7,025
OEM & Emerging Markets
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	87,206	62,719	259,418	167,544
Intersegment revenue	(11,456)	(7,518)	(29,986)	(24,528)
Earnings from operations	26,931	20,658	77,628	48,100
Maritime
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	42,256	40,586	145,909	147,469
Intersegment revenue	(567)	(656)	(1,865)	(2,728)
Earnings from operations	4,466	3,155	19,060	16,482
Detection
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	31,356	26,417	89,881	91,391
Intersegment revenue	(2)	0	(3)	(31)
Earnings from operations	8,883	6,999	24,644	25,556
Eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Intersegment revenue	(26,000)	(18,151)	(62,670)	(55,340)
Total Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Earnings from operations	$ 121,310	$ 104,602	$ 308,111	$ 268,305